Multi-drop unidirectional services in a network

ABSTRACT

Systems and methods for a multi-drop, unidirectional service in a network include, responsive to a source point, one or more drop points, and a routing consideration, computing a path in the network; causing establishment of the multi-drop, unidirectional service on the computed path, through one of a control plane and a Software Defined Networking (SDN) controller; and managing the multi-drop, unidirectional service through the one of the control plane and the SDN controller. The multi-drop, unidirectional service has the source point at an originating node, one or more drop points at associated intermediate nodes, zero or more intermediate nodes with no drop points, and one or more drop points at associated terminating nodes.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present patent application/patent claims the benefit of priority ofIndian Patent Application No. 201611000933, filed on Jan. 11, 2016, andentitled “MULTI-DROP UNIDIRECTIONAL SERVICES IN A NETWORK,” the contentsof which are incorporated in full by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to networking systems andmethods. More particularly, the present disclosure relates tomulti-drop, unidirectional services in a network with a control planeand/or under Software Defined Networking (SDN) control.

BACKGROUND OF THE DISCLOSURE

Optical networks and the like (e.g., Dense Wave Division Multiplexing(DWDM), Synchronous Optical Network (SONET), Synchronous DigitalHierarchy (SDH), Optical Transport Network (OTN), Ethernet, and thelike) at various layers are deploying control plane systems and methods.Control planes provide an automatic allocation of network resources inan end-to-end manner. Exemplary control planes may include AutomaticallySwitched Optical Network (ASON) as defined in ITU-T G.8080/Y.1304,Architecture for the automatically switched optical network (ASON)(02/2005), the contents of which are herein incorporated by reference;Generalized Multi-Protocol Label Switching (GMPLS) Architecture asdefined in IETF Request for Comments (RFC): 3945 (10/2004) and the like,the contents of which are herein incorporated by reference; OpticalSignaling and Routing Protocol (OSRP) from Ciena Corporation which is anoptical signaling and routing protocol similar to PrivateNetwork-to-Network Interface (PNNI) and Multi-Protocol Label Switching(MPLS); or any other type control plane for controlling network elementsat multiple layers, and establishing connections among nodes. Controlplanes are configured to establish end-to-end signaled connections suchas Subnetwork Connections (SNCs) in ASON or OSRP and Label SwitchedPaths (LSPs) in GMPLS and MPLS. Note, as described herein, SNCs and LSPscan generally be referred to as services in the control plane. Also,note the aforementioned control planes are circuit-based control planes,e.g., operating at Layer 1 (Time Division Multiplexing (TDM)) and/orLayer 0 (wavelengths). Control planes use the available paths to routethe services and program the underlying hardware accordingly.

In addition to control planes which are distributed, a centralizedmethod of control exists with Software Defined Networking (SDN) whichutilizes a centralized controller. SDN is an emerging framework whichincludes a centralized control plane decoupled from the data plane. SDNprovides the management of network services through abstraction oflower-level functionality. This is done by decoupling the system thatmakes decisions about where traffic is sent (the control plane) from theunderlying systems that forward traffic to the selected destination (thedata plane). Examples of SDN include OpenFlow (www.opennetworking.org),General Switch Management Protocol (GSMP) defined in RFC 3294 (June2002), and Forwarding and Control Element Separation (ForCES) defined inRFC 5810 (March 2010), the contents of all are incorporated by referenceherein. Note, distributed control planes can be used in conjunction withcentralized controllers in a hybrid deployment.

Advantageously, control plane and/or SDN management provide a rich setof Operations, Administration, Maintenance, and Provisioning (OAM&P)features for underlying services in the network. One particular type ofservice may include a multi-drop, unidirectional service. Note,typically most network services are bi-directional between a source nodeand a destination node. A unidirectional service only transmits from thesource node to the destination node. A multi-drop unidirectional servicetransmits from the source node to the destination node with one or moreintermediate drops of the service at intermediate nodes. An example of amulti-drop, unidirectional service may include a video broadcast.Conventionally, multi-drop, unidirectional services are manuallysupported in optical networks with manual Flexible Cross Connects (FCCs)provisioned at the intermediate nodes. Disadvantageously, the manualsupport for these services does not allow the use of the rich set ofmanagement features in control planes and/or SDN such as routecalculation, mesh restoration, single point and click configuration, andthe like.

BRIEF SUMMARY OF THE DISCLOSURE

In an exemplary embodiment, a method for a multi-drop, unidirectionalservice in a network includes, responsive to a source point, one or moredrop points, and a routing consideration, computing a path in thenetwork; causing establishment of the multi-drop, unidirectional serviceon the computed path, through one of a control plane and a SoftwareDefined Networking (SDN) controller; and managing the multi-drop,unidirectional service through the one of the control plane and the SDNcontroller. The multi-drop, unidirectional service has the source pointat an originating node, one or more drop points at associatedintermediate nodes, zero or more intermediate nodes with no drop points,and one or more drop points at associated terminating nodes. Themanaging can include, responsive to a fault in the network affecting oneor more drop points, causing mesh restoration for an alternate path tothe affected one or more drop points; and causing establishment of thealternate path. The managing can include, responsive to a change in droppoints the one or more drop points, implementing the change withoutaffecting the one or more drop points.

The managing can include, at an intermediate node, utilizing a FlexibleCross Connect with a single Virtual Connection Point used only forbridging. The routing consideration can include one of optimal bandwidthwhere common sections are leveraged to multiple drop points, shortestpath where a shortest path is used to each of the one or more droppoints, and a user designated route where a user specifies the path. Themanaging can utilize the routing consideration during service creation,mesh restoration, and addition or deletion of drop points and adherenceto the routing considerations is via a best effort to avoid any servicedisruption for existing drop points. The method can further includeutilizing part of the computed path for a second multi-drop,unidirectional service, in an opposite direction as the multi-drop,unidirectional service. The multi-drop, unidirectional service can be aLayer 1 Time Division Multiplexing (TDM) service.

In another exemplary embodiment, a node in a network supporting amulti-drop, unidirectional service includes one or more ports; and acontroller communicatively coupled to the one or more ports, wherein thecontroller is configured to, responsive to a source point, one or moredrop points, and a routing consideration, compute a path in the network,cause establishment of the multi-drop, unidirectional service on thecomputed path, through one of a control plane and a Software DefinedNetworking (SDN) controller, and manage the multi-drop, unidirectionalservice through the one of the control plane and the SDN controller. Themulti-drop, unidirectional service has the source point at anoriginating node, one or more drop points at associated intermediatenodes, zero or more intermediate nodes with no drop points, and one ormore drop points at associated terminating nodes. To manage themulti-drop, unidirectional service, the controller can be configured to,responsive to a fault in the network affecting one or more drop points,cause mesh restoration for an alternate path to the affected one or moredrop points, and cause establishment of the alternate path. To managethe multi-drop, unidirectional service, the controller can be configuredto, responsive to a change in drop points the one or more drop points,cause the change without causing a service disruption for the existingone or more drop points.

To manage the multi-drop, unidirectional service, the controller isconfigured to utilize a Flexible Cross Connect with a single VirtualConnection Point used only for bridging. The routing consideration caninclude one of optimal bandwidth where common sections are leveraged tomultiple drop points, shortest path where a shortest path is used toeach of the one or more drop points, and a user designated route where auser specifies the path. To manage the multi-drop, unidirectionalservice, the controller can be configured to utilize the routingconsideration during service creation, mesh restoration, and addition ordeletion of drop points and adherence to the routing considerations isvia a best effort to avoid any service disruption for existing droppoints. The controller can be configured to utilize part of the computedpath for a second multi-drop, unidirectional service, in an oppositedirection as the multi-drop, unidirectional service. The multi-drop,unidirectional service can be a Layer 1 Time Division Multiplexing (TDM)service.

In a further exemplary embodiment, a network supporting a multi-drop,unidirectional service includes a plurality of nodes interconnected toone another via a plurality of links; wherein the multi-drop,unidirectional service is established based on a computed pathresponsive to a source point, one or more drop points, and a routingconsideration, through one of a control plane and a Software DefinedNetworking (SDN) controller, and wherein the control plane and the SDNcontroller are configured to manage the multi-drop, unidirectionalservice. The multi-drop, unidirectional service has the source point atan originating node, one or more drop points at associated intermediatenodes, zero or more intermediate nodes with no drop points, and one ormore drop points at associated terminating nodes.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated and described herein withreference to the various drawings, in which like reference numbers areused to denote like system components/method steps, as appropriate, andin which:

FIG. 1 is a network diagram of an exemplary network with variousinterconnected nodes;

FIG. 2 is a block diagram of an exemplary node for use with the systemsand methods described herein;

FIG. 3 is a block diagram of a controller to provide control planeprocessing and/or OAM&P for the node, and/or to implement the SDNcontroller;

FIG. 4 is a network diagram of a network with interconnected nodes witha multi-drop, unidirectional service;

FIG. 5 is a logical diagram of bridging on an intermediate node with adrop point and with various branches of a multi-drop, unidirectionalservice;

FIG. 6 is a flowchart of a multi-drop, unidirectional service setupprocess;

FIG. 7 is a network diagram of an example of optimal bandwidth routingfor a multi-drop, unidirectional service; and

FIG. 8 is a network diagram of an example of shortest path routing for amulti-drop, unidirectional service.

DETAILED DESCRIPTION OF THE DISCLOSURE

Again, in various exemplary embodiments, the present disclosure relatesto multi-drop, unidirectional services in a network with a control planeand/or under SDN control. Specifically, systems and methods aredescribed providing a new multi-drop, unidirectional service that can bemanaged by a control plane and/or SDN. The multi-drop, unidirectionalservice supports multiple drop points as well as multicast networktraffic. Since the multi-drop, unidirectional service is unidirectional,bandwidth in the other direction can be utilized for anotherunidirectional traffic flow through the control plane and/or SDN. Thesystems and methods support hitless addition/deletion of drop points atintermediate nodes via the control plane and/or SDN. Also, the systemsand methods enable bandwidth optimization for a shared path for trafficdistribution to the intermediate drop points. The systems and methodsoffer bandwidth optimization such as the use of opposite directionbandwidth, mesh restoration support for unidirectional traffic, and easeof configuration as compared to manual FCC configuration on multiplenodes in the path.

In an exemplary embodiment, the multi-drop, unidirectional service is amulti-drop unidirectional SNC for Synchronous Optical Network (SONET),Synchronous Digital Hierarchy (SDN), or Optical Transport Network (OTN)traffic. The multi-drop, unidirectional service can also be an LSP inGMPLS or flow in SDN, as well as support other protocols. Forillustration purposes, the foregoing descriptions reference themulti-drop, unidirectional service as an SNC, but those of ordinaryskill in the art will appreciate the multi-drop, unidirectional servicecould equally apply to LSPs, flows, and other managed services by acontrol plane and/or SDN control. The multi-drop, unidirectional serviceis mesh restorable and support multicast services across an opticalbackbone network. A drop-and-continue configuration is supported onintermediate nodes, and addition and deletion of drop points are hitlesswithout affecting traffic on existing drop points. From a terminologyperspective, multi-drop unidirectional means traffic is carried in onedirection from a source node to one or more terminating drops which caninclude intermediate nodes and a destination node. Unlike existing SNCs,a multi-drop SNC has multiple termination points. There will be multipleterminating nodes each node having a single or multiple drop points.Each node on the path will be capable of dropping and/or continuing thetraffic.

Exemplary Network

Referring to FIG. 1, in an exemplary embodiment, a network diagramillustrates an exemplary network 10 with various interconnected nodes 12(illustrated as nodes 12A-12J). The nodes 12 are interconnected througha plurality of links 14. The nodes 12 communicate with one another overthe links 14 through Layer 0 (L0), Layer 1 (L1), Layer 2 (L2), and/orLayer 3 (L3) protocols. For example, L0 can be the DWDM layer, L1 can bethe Time Division Multiplexing (TDM) layer with SONET, SDH, or OTN, andL2/L3 can be packet. The nodes 12 can be network elements which includea plurality of ingress and egress ports forming the links 12. Anexemplary node implementation is illustrated in FIG. 2. The network 10can include various services between the nodes 12. Each service can beat any of the L0, L1, L2, and/or L3 protocols, such as a wavelength, anSNC, an LSP, etc., and each service is an end-to-end path or anend-to-end signaled path and from the view of the client signalcontained therein, it is seen as a single network segment managed by acontrol plane 16 and/or an SDN controller 18. The nodes 12 can also bereferred to interchangeably as network elements (NEs). The network 10 isillustrated, for example, as an interconnected mesh network, and thoseof ordinary skill in the art will recognize the network 10 can includeother architectures, along with additional nodes 12 or with fewer nodes12, etc.

The network 10 can include the control plane 16 operating on and/orbetween the nodes 12. The control plane 16 includes software, processes,algorithms, etc. that control configurable features of the network 10,such as automating discovery of the nodes 12, capacity on the links 14,port availability on the nodes 12, connectivity between ports;dissemination of topology and bandwidth information between the nodes12; calculation and creation of paths for connections; network levelprotection and mesh restoration; and the like. In an exemplaryembodiment, the control plane 16 can utilize ASON, GMPLS, OSRP, MPLS,Open Shortest Path First (OSPF), Intermediate System-Intermediate System(IS-IS), or the like. Those of ordinary skill in the art will recognizethe network 10 and the control plane 16 can utilize any type of controlplane for controlling the nodes 12 and establishing connections betweenthe nodes 12.

The SDN controller 18 can also be communicatively coupled to the network10 through one or more of the nodes 12. SDN is an emerging frameworkwhich includes a centralized control plane decoupled from the dataplane. SDN provides the management of network services throughabstraction of lower-level functionality. This is done by decoupling thesystem that makes decisions about where traffic is sent (the controlplane) from the underlying systems that forward traffic to the selecteddestination (the data plane). SDN works with the SDN controller 18knowing a full network topology through configuration or through the useof a controller-based discovery process in the network 10. The SDNcontroller 18 differs from a management system in that it controls theforwarding behavior of the nodes 12 only, and performs control in realtime or near real time, reacting to changes in services requested,network traffic analysis and network changes such as failure anddegradation. Also, the SDN controller 18 provides a standard northboundinterface to allow applications to access network resource informationand policy-limited control over network behavior or treatment ofapplication traffic. The SDN controller 18 sends commands to each of thenodes 12 to control matching of data flows received and actions to betaken, including any manipulation of packet contents and forwarding tospecified egress ports.

Note, the network 10 can use the control plane 16 separately from theSDN controller 18. Alternatively, the network 10 can use the SDNcontroller 18 separately from the control plane 16. In another exemplaryembodiment, the control plane 16 can operate in a hybrid control modewith the SDN controller 18. In this scheme, for example, the SDNcontroller 18 does not necessarily have a complete view of the network10. Here, the control plane 16 can be used to manage services inconjunction with the SDN controller 18.

In the terminology of ASON and OSRP, sub-network connections (SNC) areend-to-end signaled paths since from the point of view of a clientsignal, each is a single network segment. In GMPLS, the connections arean end-to-end path referred to as LSPs. For example, LSPs for GMPLS aredescribed in draft-ietf-ccamp-gmpls-ospf-g709v3-13, “Traffic EngineeringExtensions to OSPF for Generalized MPLS (GMPLS) Control of EvolvingG.709 OTN Networks,” (Dec. 11, 2013), the contents of which areincorporated by reference herein. In SDN, such as in OpenFlow, servicesare called “flows.” In the various descriptions herein, reference ismade to SNCs for illustration only of an exemplary embodiment of thesystems and methods. Those of ordinary skill in the art will recognizethat SNCs, LSPs, flows, or any other managed service in the network canbe used with the systems and methods described herein. Also, asdescribed herein, the term services is used for generally describingconnections such as SNCs, LSPs, flows, etc. in the network 10.

Exemplary Network Element/Node

Referring to FIG. 2, in an exemplary embodiment, a block diagramillustrates an exemplary node 30 for use with the systems and methodsdescribed herein. In an exemplary embodiment, the exemplary node 30 canbe a network element that may consolidate the functionality of aMulti-Service Provisioning Platform (MSPP), Digital Cross-Connect (DCS),Ethernet and/or Optical Transport Network (OTN) switch, Wave DivisionMultiplexed (WDM)/Dense WDM (DWDM) platform, etc. into a single,high-capacity intelligent switching system providing Layer 0, 1, and/or2 consolidation. In another exemplary embodiment, the node 30 can be anyof an OTN Add/Drop Multiplexer (ADM), a Multi-Service ProvisioningPlatform (MSPP), a Digital Cross-Connect (DCS), an opticalcross-connect, an optical switch, a router, a switch, a WavelengthDivision Multiplexing (WDM) terminal, an access/aggregation device, etc.That is, the node 30 can be any digital system with ingress and egressdigital signals and switching of channels, timeslots, tributary units,etc. While the node 30 is generally shown as an optical network element,the systems and methods contemplated for use with any switching fabric,network element, or network based thereon.

In an exemplary embodiment, the node 30 includes common equipment 32,one or more line modules 34, and one or more switch modules 36. Thecommon equipment 32 can include power; a control module; Operations,Administration, Maintenance, and Provisioning (OAM&P) access; userinterface ports; and the like. The common equipment 32 can connect to amanagement system 38 through a data communication network 40 (as well asa Path Computation Element (PCE), the SDN controller 18, OpenFlowcontroller, etc.). The management system 38 can include a networkmanagement system (NMS), element management system (EMS), or the like.Additionally, the common equipment 32 can include a control planeprocessor, such as a controller 50 illustrated in FIG. 3 configured tooperate the control plane as described herein. The node 30 can includean interface 42 for communicatively coupling the common equipment 32,the line modules 34, and the switch modules 36 to one another. Forexample, the interface 42 can be a backplane, midplane, a bus, opticalor electrical connectors, or the like. The line modules 34 areconfigured to provide ingress and egress to the switch modules 36 and toexternal connections on the links to/from the node 30. In an exemplaryembodiment, the line modules 34 can form ingress and egress switcheswith the switch modules 36 as center stage switches for a three-stageswitch, e.g. a three-stage Clos switch. Other configurations and/orarchitectures are also contemplated. The line modules 34 can includeoptical transceivers, such as, for example, 1 Gb/s (GbE PHY), 2.5 GB/s(OC-48/STM-1, OTU1, ODU1), 10 Gb/s (OC-192/STM-64, OTU2, ODU2, 10 GbEPHY), 40 Gb/s (OC-768/STM-256, OTU3, ODU3, 40 GbE PHY), 100 Gb/s (OTU4,ODU4, 100 GbE PHY), ODUflex, Flexible Ethernet, etc.

Further, the line modules 34 can include a plurality of opticalconnections per module and each module may include a flexible ratesupport for any type of connection, such as, for example, 155 MB/s, 622MB/s, 1 GB/s, 2.5 GB/s, 10 GB/s, 40 GB/s, and 100 GB/s, N×1.25 GB/s, andany rate in between as well as future, higher rates. The line modules 34can include WDM interfaces, short reach interfaces, and the like, andcan connect to other line modules 34 on remote network elements, endclients, edge routers, and the like, e.g. forming connections on thelinks in the network 100. From a logical perspective, the line modules34 provide ingress and egress ports to the node 30, and each line module34 can include one or more physical ports. The switch modules 36 areconfigured to switch channels, timeslots, tributary units, packets, etc.between the line modules 34. For example, the switch modules 36 canprovide wavelength granularity (Layer 0 switching); OTN granularity suchas Optical Channel Data Unit-1 (ODU1), Optical Channel Data Unit-2(ODU2), Optical Channel Data Unit-3 (ODU3), Optical Channel Data Unit-4(ODU4), Optical Channel Data Unit-flex (ODUflex), Optical channelPayload Virtual Containers (OPVCs), ODTUGs, etc.; Ethernet granularity;and the like. Specifically, the switch modules 36 can include TimeDivision Multiplexed (TDM) (i.e., circuit switching) and/or packetswitching engines. The switch modules 36 can include redundancy as well,such as 1:1, 1:N, etc. In an exemplary embodiment, the switch modules 36provide OTN switching and/or Ethernet switching.

The nodes 12 in the network 10 can include the node 30. Those ofordinary skill in the art will recognize the node 30 can include othercomponents which are omitted for illustration purposes, and that thesystems and methods described herein are contemplated for use with aplurality of different network elements with the node 30 presented as anexemplary type of network element. For example, in another exemplaryembodiment, the node 30 may not include the switch modules 36, butrather have the corresponding functionality in the line modules 34 (orsome equivalent) in a distributed fashion. For the node 30, otherarchitectures providing ingress, egress, and switching are alsocontemplated for the systems and methods described herein. In general,the systems and methods described herein contemplate use with anynetwork element providing switching of channels, timeslots, tributaryunits, wavelengths, etc. and using the control plane. Furthermore, thenode 30 is merely presented as one exemplary node 30 for the systems andmethods described herein.

Exemplary Controller

Referring to FIG. 3, in an exemplary embodiment, a block diagramillustrates a controller 50 to provide control plane processing and/orOAM&P for the node 30, and/or to implement the SDN controller 18. Thecontroller 50 can be part of the common equipment, such as commonequipment 32 in the node 30, or a stand-alone device communicativelycoupled to the node 30 via the DCN 40. In a stand-alone configuration,the controller 50 can be the SDN controller 18, an NMS, a PCE, etc. Thecontroller 50 can include a processor 52 which is a hardware device forexecuting software instructions such as operating the control plane. Theprocessor 52 can be any custom made or commercially available processor,a central processing unit (CPU), an auxiliary processor among severalprocessors associated with the controller 50, a semiconductor-basedmicroprocessor (in the form of a microchip or chip set), or generallyany device for executing software instructions. When the controller 50is in operation, the processor 52 is configured to execute softwarestored within the memory, to communicate data to and from the memory,and to generally control operations of the controller 50 pursuant to thesoftware instructions. The controller 50 can also include a networkinterface 54, a data store 56, memory 58, an I/O interface 60, and thelike, all of which are communicatively coupled to one another and withthe processor 52.

The network interface 54 can be used to enable the controller 50 tocommunicate on the DCN 40, such as to communicate control planeinformation to other controllers, to the management system 38, to thenodes 30, and the like. The network interface 54 can include, forexample, an Ethernet card (e.g., 10 BaseT, Fast Ethernet, GigabitEthernet) or a wireless local area network (WLAN) card (e.g., 802.11).The network interface 54 can include address, control, and/or dataconnections to enable appropriate communications on the network. Thedata store 56 can be used to store data, such as control planeinformation, provisioning data, OAM&P data, etc. The data store 56 caninclude any of volatile memory elements (e.g., random access memory(RAM, such as DRAM, SRAM, SDRAM, and the like)), nonvolatile memoryelements (e.g., ROM, hard drive, flash drive, CDROM, and the like), andcombinations thereof. Moreover, the data store 56 can incorporateelectronic, magnetic, optical, and/or other types of storage media. Thememory 58 can include any of volatile memory elements (e.g., randomaccess memory (RAM, such as DRAM, SRAM, SDRAM, etc.)), nonvolatilememory elements (e.g., ROM, hard drive, flash drive, CDROM, etc.), andcombinations thereof. Moreover, the memory 58 may incorporateelectronic, magnetic, optical, and/or other types of storage media. Notethat the memory 58 can have a distributed architecture, where variouscomponents are situated remotely from one another, but may be accessedby the processor 52. The I/O interface 60 includes components for thecontroller 50 to communicate with other devices. Further, the I/Ointerface 60 includes components for the controller 50 to communicatewith the other nodes, such as using overhead associated with OTNsignals.

In an exemplary embodiment, the controller 50 is configured tocommunicate with other controllers 50 in the network 10 to operate thecontrol plane for control plane signaling. This communication may beeither in-band or out-of-band. For SONET networks and similarly for SDHnetworks, the controllers 50 may use standard or extended line (orsection) overhead for in-band signaling, such as the Data CommunicationsChannels (DCC). Out-of-band signaling may use an overlaid InternetProtocol (IP) network such as, for example, User Datagram Protocol (UDP)over IP. In an exemplary embodiment, the controllers 50 can include anin-band signaling mechanism utilizing OTN overhead. The GeneralCommunication Channels (GCC) defined by ITU-T Recommendation G.709 arein-band side channels used to carry transmission management andsignaling information within Optical Transport Network elements. The GCCchannels include GCC0 and GCC1/2. GCCO are two bytes within OpticalChannel Transport Unit-k (OTUk) overhead that are terminated at every 3R(Re-shaping, Re-timing, Re-amplification) point. GCC1/2 are four bytes(i.e. each of GCC1 and GCC2 include two bytes) within Optical ChannelData Unit-k (ODUk) overhead. For example, GCC0, GCC1, GCC2 or GCC1+2 maybe used for in-band signaling or routing to carry control plane traffic.Based on the intermediate equipment's termination layer, different bytesmay be used to carry control plane signaling. If the ODU layer hasfaults, it has been ensured not to disrupt the GCC1 and GCC2 overheadbytes and thus achieving the proper delivery control plane signaling.Other mechanisms are also contemplated for control plane and/or SDNsignaling.

The controller 50 is configured to operate the control plane 16 in thenetwork 10. That is, the controller 50 is configured to implementsoftware, processes, algorithms, etc. that control configurable featuresof the network 10, such as automating discovery of the nodes, capacityon the links, port availability on the nodes, connectivity betweenports; dissemination of topology and bandwidth information between thenodes; path computation and creation for connections; network levelprotection and restoration; and the like. As part of these functions,the controller 50 can include a topology database that maintains thecurrent topology of the network 10 based on control plane signaling(e.g., HELLO messages) and a connection database that maintainsavailable bandwidth on the links 14 again based on the control planesignaling. Again, the control plane is a distributed control plane;thus, a plurality of the controllers 50 can act together to operate thecontrol plane using the control plane signaling to maintain databasesynchronization. In source-based routing, the controller 50 at a sourcenode for a connection is responsible for path computation andestablishing by signaling other controllers 50 in the network 10, suchas through a SETUP message. For example, the source node and itscontroller 50 can signal a path through various techniques such asResource Reservation Protocol-Traffic Engineering (RSVP-TE) (G.7713.2),Private Network-to-Network Interface (PNNI), Constraint-based RoutingLabel Distribution Protocol (CR-LDP), etc. and the path can be signaledas a Designated Transit List (DTL) in PNNI or an Explicit Route Object(ERO) in RSVP-TE/CR-LDP. As described herein, the connection refers to asignaled, end-to-end connection such as an SNC, SNCP, LSP, etc. whichare generally a service. Path computation generally includes determininga path, i.e. traversing the links through the nodes from the originatingnode to the destination node based on a plurality of constraints such asadministrative weights on the links, bandwidth availability on thelinks, etc.

Multi-Drop, Unidirectional Service

Referring to FIG. 4, in an exemplary embodiment, a network diagramillustrates a network 10A with interconnected nodes 12A-12G with amulti-drop, unidirectional service 70. The node 12A is the originatingnode (also referred to as the source node). The node 12B is anintermediate node with a drop point. The nodes 12C, 12D are intermediatenodes without drop points, but with branches for the multi-drop,unidirectional service 70. Specifically, intermediate nodes can havedrop points, no drop points, branches, and no branches. A branch is nota drop point, but a point where the multi-drop, unidirectional service70 egresses to more than one link 14. The intermediate nodes withoutdrop points simply forward the traffic associated with the multi-drop,unidirectional service 70. The nodes 12E, 12F, 12G are terminating nodes(also referred to as destination nodes). Thus, in operation, themulti-drop, unidirectional service 70 from the node 12A provides trafficto the nodes 12B, 12E, 12F, 12G and the traffic transits through thenodes 12C, 12D.

In an exemplary embodiment, the multi-drop, unidirectional service 70 isimplemented by creating Unidirectional-Flexible-Cross-Connects (UFCC)instead of Permanent Virtual Circuits (PVC) (cross-connects). FCCs useVirtual Connection Points (VCP) for bridging the traffic on originating,intermediate and terminating nodes. A VCP is a logical object that ismaintained in software that defines a connection between real networkresources in hardware, as well as other logical objects. The VCP has apoint of input selection. Due to its unidirectional nature, it acts as asource connection point for multicasting. The use of VCPs enablesefficient multicast, drop-and-continue, protection, bridge-and-roll,test access point, and circuit switching applications, among others.VCPs are described, for example, in commonly assigned U.S. Pat. No.8,509,113 issued on Aug. 13, 2013, and entitled “METHODS AND SYSTEMS FORMANAGING DIGITAL CROSS-CONNECT MATRICES USING VIRTUAL CONNECTIONPOINTS,” the contents of which are incorporated by reference. As themulti-drop, unidirectional service 70 is unidirectional, a selectionmechanism is not required. Drop ports can be dynamically created/deletedon intermediate nodes also.

In a conventional SNC, cross connects are created on originating,intermediate and terminating nodes. These cross connects have a singlesource and a single sink in each direction. The conventional SNC usesboth a selection and bridging mechanism whereas in the multi-drop,unidirectional service 70, the SNC selection mechanism is not requiredas there is no traffic in the return direction.

Referring to FIG. 5, in an exemplary embodiment, a logical diagramillustrates bridging on an intermediate node 12-1 with a drop point 80and with various branches 82 for a multi-drop, unidirectional service70A. In this example, the node 12-1 is an intermediate node, receivingthe multi-drop, unidirectional service 70A from an originating node12-0. The node 12-1 includes various Connection Termination Points(CTPs) 90A, 90B, 90C, 90D, 90E. The multi-drop, unidirectional service70A from the originating node 12-0 is coupled to the CTP 90A, providingthe multi-drop, unidirectional service 70A to a bridge 92 which includea VCP 94. The multi-drop, unidirectional service 70A has one FCC 96 pernode. The FCC 96 includes a single VCP 94 used only for bridging alongwith the CTPs 90. The VCP 94, acting as a sink, will source from theingress port, i.e., the CTP 90A. The same VCP 94 will act as a sourceand will sink to single/multiple egress ports, i.e., the CTPs 90B, 90C,90D, 90E.

Multi-Drop, Unidirectional Service Setup

Referring to FIG. 6, in an exemplary embodiment, a flowchart illustratesa multi-drop, unidirectional service setup process 100. The multi-drop,unidirectional service setup process 100 can be implemented via thenodes 12, the control plane 16, and/or the SDN controller 18. First, theprocess 100 includes specifying a source point, one or more drop points,and routing considerations (step 102). To set up the multi-drop,unidirectional service 70, one or more drop points have to be specifiedon the nodes 12. For example, during SNC set up, a user can specify onesource point and one or more drop points. Each drop point can have itsown configuration (route) and status parameters (connection status anddiagnostics). The routing considerations can be specified for pathcomputation and may be based on optimal bandwidth, a shortest path, or auser designated route. On selecting the user designated route option,the user will be allowed to add a route to every drop point. If norouting consideration is selected, the process 100 can be based on theoptimal bandwidth. Connection status and diagnostics will be specific toa drop point. Even if one of the drop points is not reachable,connections to other drop points can still be set-up.

Referring to FIGS. 7 and 8, in exemplary embodiments, network diagramsillustrate examples of optimal bandwidth routing 150 (FIG. 7) andshortest path routing 160 (FIG. 8) for a multi-drop, unidirectionalservice 70B. Again, the process 100 can include configurable routingconsiderations. In FIG. 7, for the optimal bandwidth routing 150,individual routes to multiple drop points may have common sections. Thiscan be leveraged to prevent traffic duplication on the common sectionsthus optimizing network bandwidth. In FIG. 8, for the shortest pathrouting 152, for each drop point shortest available path will becalculated. This is irrespective of whether there is scope for bandwidthsharing or not, the routes used will be on the basis of shortest pathcalculated. If the shortest paths calculated for multi-drops converge atsome section, bandwidth optimization can be used to avoid trafficduplication.

For the user designated route, with this option, the user can specify aroute to each drop point. Once selected, routes should be specified toall the drop points. If routes are not selected to all drop points,routes to each of the drop points can be calculated based on the otherselected criterion. The user can also specify whether the routes to thedrop points will be exclusive or not. The routing considerations can beadhered to at the time of setup, mesh restoration, and addition ordeletion of drop points.

Returning back to FIG. 6, path computation is performed for themulti-drop, unidirectional service 70 based on the source point, the oneor more drop points, and the routing considerations (step 104). Once thepath is computed, connection establishment occurs on the computed path(step 106). The connection establishment can be through the controlplane 16 and/or the SDN controller 18. Once established, the multi-drop,unidirectional service 70 operates in the network (step 108).

During the operation (step 108), a fault can occur affecting one or moreof the drop points (step 110). For example, on receiving a line downevent, the originating node (or the SDN controller 18) can determine theaffected drop points and initiate mesh restoration for only these droppoints (step 112). The unaffected drop points will not be a part of themesh restoration thus making mesh restoration hitless for them. The newroute calculation (for the affected drop points) can be based on routingconsideration specified in the process 100.

During the operation (step 108), addition and deletion of drop pointscan happen on any node for the multi-drop, unidirectional service 70(step 114). The addition and deletion of drop points can happen on anynode, namely intermediate nodes, existing terminating nodes, as well asnodes not currently part of a path on the current multi-drop,unidirectional service 70. For deletion of drop ports, the process 100can include removing the associated connections, via the control plane16 and/or the SDN controller 18, without impacting in-service droppoints. For new drop ports, route calculation for the new drop points isdone on the basis of the routing consideration setting (step 116), andthe new route links are established, without impacting in-service droppoints.

Referring back to FIG. 5, for example, the deletion of the drop point 80occurs by adjusting the VCP 94 to remove the drop point 80, withoutaffecting the CTPs 90C, 90D, 90E. Those of ordinary skill in the artwill appreciate various other reconfigurations are possible based on theFCC 96. Changes to the FCC 96 are performed without affectingnon-changing aspects.

It will be appreciated that some exemplary embodiments described hereinmay include one or more generic or specialized processors (“one or moreprocessors”) such as microprocessors; Central Processing Units (CPUs);Digital Signal Processors (DSPs): customized processors such as NetworkProcessors (NPs) or Network Processing Units (NPUs), Graphics ProcessingUnits (GPUs), or the like; Field Programmable Gate Arrays (FPGAs); andthe like along with unique stored program instructions (including bothsoftware and firmware) for control thereof to implement, in conjunctionwith certain non-processor circuits, some, most, or all of the functionsof the methods and/or systems described herein. Alternatively, some orall functions may be implemented by a state machine that has no storedprogram instructions, or in one or more Application Specific IntegratedCircuits (ASICs), in which each function or some combinations of certainof the functions are implemented as custom logic or circuitry. Ofcourse, a combination of the aforementioned approaches may be used. Forsome of the exemplary embodiments described herein, a correspondingdevice such as hardware, software, firmware, and a combination thereofcan be referred to as “circuitry configured or adapted to,” “logicconfigured or adapted to,” etc. perform a set of operations, steps,methods, processes, algorithms, functions, techniques, etc. as describedherein for the various exemplary embodiments.

Moreover, some exemplary embodiments may include a non-transitorycomputer-readable storage medium having computer readable code storedthereon for programming a computer, server, appliance, device,processor, circuit, etc. each of which may include a processor toperform functions as described and claimed herein. Examples of suchcomputer-readable storage mediums include, but are not limited to, ahard disk, an optical storage device, a magnetic storage device, a ROM(Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM(Erasable Programmable Read Only Memory), an EEPROM (ElectricallyErasable Programmable Read Only Memory), Flash memory, and the like.When stored in the non-transitory computer readable medium, software caninclude instructions executable by a processor or device (e.g., any typeof programmable circuitry or logic) that, in response to such execution,cause a processor or the device to perform a set of operations, steps,methods, processes, algorithms, functions, techniques, etc. as describedherein for the various exemplary embodiments.

Although the present disclosure has been illustrated and describedherein with reference to preferred embodiments and specific examplesthereof, it will be readily apparent to those of ordinary skill in theart that other embodiments and examples may perform similar functionsand/or achieve like results. All such equivalent embodiments andexamples are within the spirit and scope of the present disclosure, arecontemplated thereby, and are intended to be covered by the followingclaims.

What is claimed is:
 1. A method for a multi-drop, unidirectional servicein a network, the method comprising: responsive to a source point, oneor more drop points, and a routing consideration, computing a path inthe network; causing establishment of the multi-drop, unidirectionalservice on the computed path, through one of a control plane and aSoftware Defined Networking (SDN) controller; and managing themulti-drop, unidirectional service through the one of the control planeand the SDN controller.
 2. The method of claim 1, wherein themulti-drop, unidirectional service has the source point at anoriginating node, one or more drop points at associated intermediatenodes, zero or more intermediate nodes with no drop points, and one ormore drop points at associated terminating nodes.
 3. The method of claim1, wherein the managing comprises: responsive to a fault in the networkaffecting one or more drop points, causing mesh restoration for analternate path to the affected one or more drop points; and causingestablishment of the alternate path.
 4. The method of claim 1, whereinthe managing comprises: responsive to a change in drop points the one ormore drop points, implementing the change without affecting the one ormore drop points.
 5. The method of claim 1, wherein the managingcomprises, at an intermediate node: utilizing a Flexible Cross Connectwith a single Virtual Connection Point used only for bridging.
 6. Themethod of claim 1, wherein the routing consideration comprises one ofoptimal bandwidth where common sections are leveraged to multiple droppoints, shortest path where a shortest path is used to each of the oneor more drop points, and a user designated route where a user specifiesthe path.
 7. The method of claim 1, wherein the managing utilizes therouting consideration during service creation, mesh restoration, andaddition or deletion of drop points and adherence to the routingconsiderations is via a best effort to avoid any service disruption forexisting drop points.
 8. The method of claim 1, further comprising:utilizing part of the computed path for a second multi-drop,unidirectional service, in an opposite direction as the multi-drop,unidirectional service.
 9. The method of claim 1, wherein themulti-drop, unidirectional service is a Layer 1 Time DivisionMultiplexing (TDM) service.
 10. A node in a network supporting amulti-drop, unidirectional service, the node comprising: one or moreports; and a controller communicatively coupled to the one or moreports, wherein the controller is configured to responsive to a sourcepoint, one or more drop points, and a routing consideration, compute apath in the network, cause establishment of the multi-drop,unidirectional service on the computed path, through one of a controlplane and a Software Defined Networking (SDN) controller, and manage themulti-drop, unidirectional service through the one of the control planeand the SDN controller.
 11. The node of claim 10, wherein themulti-drop, unidirectional service has the source point at anoriginating node, one or more drop points at associated intermediatenodes, zero or more intermediate nodes with no drop points, and one ormore drop points at associated terminating nodes.
 12. The node of claim10, wherein, to manage the multi-drop, unidirectional service, thecontroller is configured to responsive to a fault in the networkaffecting one or more drop points, cause mesh restoration for analternate path to the affected one or more drop points, and causeestablishment of the alternate path.
 13. The node of claim 10, wherein,to manage the multi-drop, unidirectional service, the controller isconfigured to responsive to a change in drop points the one or more droppoints, cause the change without causing a service disruption for theexisting one or more drop points.
 14. The node of claim 10, wherein, tomanage the multi-drop, unidirectional service, the controller isconfigured to utilize a Flexible Cross Connect with a single VirtualConnection Point used only for bridging.
 15. The node of claim 10,wherein the routing consideration comprises one of optimal bandwidthwhere common sections are leveraged to multiple drop points, shortestpath where a shortest path is used to each of the one or more droppoints, and a user designated route where a user specifies the path. 16.The node of claim 10, wherein, to manage the multi-drop, unidirectionalservice, the controller is configured to utilize the routingconsideration during service creation, mesh restoration, and addition ordeletion of drop points and adherence to the routing considerations isvia a best effort to avoid any service disruption for existing droppoints.
 17. The node of claim 10, wherein the controller is configuredto utilize part of the computed path for a second multi-drop,unidirectional service, in an opposite direction as the multi-drop,unidirectional service.
 18. The node of claim 10, wherein themulti-drop, unidirectional service is a Layer 1 Time DivisionMultiplexing (TDM) service.
 19. A network supporting a multi-drop,unidirectional service, the network comprising: a plurality of nodesinterconnected to one another via a plurality of links; wherein themulti-drop, unidirectional service is established based on a computedpath responsive to a source point, one or more drop points, and arouting consideration, through one of a control plane and a SoftwareDefined Networking (SDN) controller, and wherein the control plane andthe SDN controller are configured to manage the multi-drop,unidirectional service.
 20. The network of claim 19, wherein themulti-drop, unidirectional service has the source point at anoriginating node, one or more drop points at associated intermediatenodes, zero or more intermediate nodes with no drop points, and one ormore drop points at associated terminating nodes.